Topic 21 - Earth and Atmospheric Science Flashcards
8.18 - What are the gases produced by volcanic activity and what did they do?
Volcanoes affect the atmosphere by releasing large amounts of CO2 and water vapour, and smaller amounts of other gases like nitrogen.
There was lots of volcanic activity on early Earth, this helped form the atmosphere.
This idea is supported by planets like Mars which is a rocky planet with volcanoes. This supports the idea of early Earth having high CO2.
Volcanoes produce nitrogen which gradually built up in the atmosphere, this explains the high concentrations of nitrogen in the present atmosphere.
8.18 - Explain the evidence for the low amounts of oxygen in early Earth
Oxygen is not produced by volcanoes,
Iron pyrite, a compound broken down by oxygen forms when there is no oxygen.
2.4 billion years ago, rocks with iron oxide started to form, this oxidation suggests that oxygen levels increased at the time.
There is fossil evidence that oxygen was produced by microorganisms.
Scientists think that oxygen from these microorganisms reacted with the iron to produce insoluble iron oxide layers.
8.19 - Describe the composition of Earth’s early atmosphere
Large amount of CO2, water vapour and small amounts of gases.
Little oxygen in the atmosphere.
8.20 - Explain how oceans were formed
4 billion years ago, the Earth cooled down, resulting in water vapour in the atmosphere to condense into liquid water, forming the oceans.
8.21 - Explain how the CO2 levels changed in the atmosphere
Over millions of years, the oxygen levels increased and CO2 levels decreased.
As the Earth cooled, oceans formed and the CO2 then dissolved in the oceans, decreasing the CO2 levels in the atmosphere.
Sea creatures used CO2 for their shells of CaCO3, allowing more CO2 to be dissolved in the ocean.
8.22 - Explain how plants lead to changes in the atmosphere
Some organisms use sunlight to make food through photosynthesis.
This changes the atmosphere, by decreasing CO2 and increasing O2 levels in the blood.
Primitive plants like cyanobacteria, grew in colonies and photosynthesise.
Over time they formed rock shapes called stromatolites.
Stromatolites are over 3 billion years, this proves photosynthesis happened at that time, that caused a rise in oxygen levels in the atmosphere.
As cyanobacteria evolved into plants, oxygen levels got higher, now 21% of Earth’s atmosphere is oxygen.
Oxygen allows aerobic respiration and combustion.
8.23 - Explain the test for the presence of oxygen
Lighted splint in test tube of oxygen, it relights in the presence of oxygen.
8.24 - Explain the greenhouse effect
Energy from the Sun is transferred by waves to Earth.
Some of the energy is absorbed by the Earth’s surface, warming it up. This emits infrared waves.
Sometimes greenhouse gases in the air absorb energy transferred by the infrared waves.
The greenhouse gases re-emit the energy and warms Earth’s surface even more.
This is the greenhouse effect.
8.25 - Explain the correlation between changes in atmosphere and human activity
Since 1850, there has been a steady increase in fossil fuel consumption, combustion has increased the CO2. This is evidence that fossil fuels cause increase in CO2 levels and causes global warming.
There is a strong correlation between CO2 levels and the temperature of the Earth.
Scientists can show CO2 absorbs infrared waves, so as CO2 levels increase, less infrared waves leave Earth.
This shows how CO2 causes temperature rise .
8.25 - Evaluate the evidence for the correlation between changes in atmosphere and human activity
CO2 is measured using monitoring stations
Evidence for the composition of the atmosphere comes from ice cores, containing concentrations of CO2 in the old atmosphere.
An ice core from one area can’t show global temperature changes.
Earlier temperature measurements were not very accurate, nowadays thermometers and satellites can precisely measure temperature
8.25 - Compare correlation and causation
Correlation is a trend in a set of data.
The cause of it is found by collecting evidence and explain how the trend happens.
8.26 - Describe how human activities affect the climate
Increased burning of fossil fuels release more CO2 which causes global warming.
Methane is another greenhouse gas that absorbs more infrared radiation and is released when oil is extracted.
Cattle farming produces a lot of methane, as cows digest grass the bacteria in it produces methane.
Rising average temperatures cause the ice at the poles to melt, the extra water will raise sea levels and increase floods.
Animals may move away from their natural habitats and may become extinct if they can’t find cooler areas.
Some areas become drier and others wetter, due to extreme weather.
More CO2 released, means more acidic seawater as the gas dissolves in it. This harms organisms in the sea.
These effects can be mitigated by reducing greenhouse gas emissions but it may not be enough to lessen the effects of climate change.
All countries would need to help pay for large-scale engineering, but this could disrupt delicate ecosystems.
Impacts of climate change can be lessened by building defences like dams, however this is a risk as it can destroy habitats.
